The British Prime Minister Theresa May has refused to say if the DUP will vote for the draft Brexit deal.

The Northern Ireland party is propping up her Westminster government.

She was speaking on British radio station LBC, where she also took questions from callers.

Mrs May firmly defended the draft Brexit deal on Thursday, as she faces increasing pressure from within her own Conservative party.

She saw several high-profile resignations from her cabinet, as well as a mounting threat of a no-confidence motion from party rebels.

In a press conference, she acknowledged that leadership is never easy - especially when the stakes are so high - but that she intends to see the process through.

British Prime Minister Theresa May (left) and DUP leader Arlene Foster in Northern Ireland in July 2018 | Image: Clodagh Kilcoyne/PA Wire/PA Images

During the LBC interview Mrs May was asked if she still had the support of DUP leader Arlene Foster.

She said: "Yes, we're still working with the DUP... We will see how every member of parliament's going to vote for this deal.

"I am confident that members of parliament - when they see this deal, when it comes back, when they look at it... When this vote comes back, every individual member of parliament will decide how they vote - whether they're a member of the DUP, Conservative, Labour, all parties within the House of Commons.

"My job is to persuade - first and foremost - my Conservative benches, those who are working with us - the DUP are working with us obviously in confidence and supply - but I want to be able to say all parliamentarians, every MP: I truly believe this is the best deal for Britain".

Mrs May also denied that she has had "a testy exchange" with Mrs Foster.